Obesity is a complex condition that can affect several facets of functioning. Previous studies have found that obesity is associated with a higher prevalence of several chronic disease conditions, lower quality of life and impaired mobility in older adults. However, one component of physical functioning that has not been well studied in relationship to obesity is risk of falls. Falls and injuries related to falling are a very importan health concern in the older population. Falls can result in significant morbidity, loss of functionl independence and death. On a societal level, injuries related to falls contribute substantially to health care costs, leading to billions of dollars of expenditures each year. Although both obesity and falls are very prevalent conditions in older adults, there is very limited understanding as to how these two conditions may interact. Interestingly, there are a number of potential mechanisms through which obesity could influence the risk of falls. Prior work has identified several patient-related risk factors for falls in older adults including mobility and balance impairment, pain, depression, chronic medical conditions and physical inactivity. Previous work has also shown that obesity is associated with increased mobility and balance impairment, pain, depression, chronic medical conditions and physical inactivity. While there are multiple plausible mechanisms through which obesity could increase the risk of falling, there have been surprisingly few studies of how these two health conditions interact. Further, the studies that are available are largely cross-sectional and provide conflicting results. A deeper understanding of how obesity and falling interact would allow better identification of seniors at risk for falls, an could potentially lead to novel strategies to prevent falls. The studies proposed herein are designed to use a large, nationally representative dataset to prospectively examine whether obesity is associated with increased risk of falls, and to study which clinical factors may mediate this relationship. We will also explore whether this relationship is modified by factors such as sex, race/ethnicity, and socioeconomic status. We will then use another nationally representative dataset to analyze whether the medical costs associated with fall injuries are different in obese vs. the non-obese. The knowledge gained from the proposed work will allow for better understanding of the impact of obesity on the lives of older adults and permit better informed public health response to the health needs of an aging, obese population.